What effect does calcium have on iron absorption?

• A. Increases iron absorption
• B. Lowers iron absorption
• C. No effect on iron absorption
• D. Increases iron excretion

Answer: (B)

Calcium can reduce iron absorption because it competes for absorption in the intestinal tract and can form insoluble complexes with iron in the gut. This effect is most evident with non-heme iron (the form found in plant foods and many supplements), leading to less iron entering the bloodstream when calcium and iron are consumed together. In practice, spacing calcium-containing products apart from iron-containing meals or supplements helps optimize iron absorption.